Turkens are the French Cou-nou, meaning naked neck. The phrase has been coined because the Brit's can't decide what the French have used to breed them and as they are so large thought Turkeys. Turkeys can't cross breed with chickens so that's a load of ......
Cou-nou have mid- neck feathers, which is the sign that the derivative Transylvanian Naked neck has been crossed with another breed, perhaps many times. they now breed true so they are a breed in themselves in France. TNN's are not Turkens FrostyM so the guy you are talking to is........misinformed. If they are large they are not TNN's as there are no large TNN's in England, but there are Cou-nou cross breeds being passed off -saw one in the National show (not placed as shape and feathering all wrong).
We have Black TNN's. They are the best examples I could find in England before we moved. The hens are top show quality producing large eggs from a medium hen daily. The cockerel came from Romania. They probably have 25% of the feathers of a Wyandotte.
They are very flighty, perfect for free ranging and taste good. Downside is they go broody so often that they only produce 150 eggs a year. If they didn't go broody it would be 300.
What more do you need to know FrostyM and PM me. 99% of TNN's for sale are cross breeds that will surface in a few generations. Any neck feathers whatsoever is a previous cross. Shame -the ebay egg sellers have almost destroyed the breed as genuine TNN eggs are top dollar (we eat ours as no market here).